The findings of impacted and transmigrated maxillary and mandibular canines: a retrospective cone beam computed tomography study.

BACKGROUND: The aim of this study was to examine and evaluate the maxillary and mandibular impacted and transmigrant canines, their relationship with neighboring tissues and pathology with cone beam computed tomography (CBCT). METHODS: CBCT data of 217 patients, between January 2018 and December 2019, with a total of 293 impacted canines were retrospectively reviewed. Clinical records were also evaluated. Maxillary or mandibular localization, angulations, transmigration, lateral and premolar tooth resorption, apical dilacerations, pathological formations, presence of persistent deciduous canines and treatment methods were investigated. RESULTS: For 293 impacted canines, 237 were in the maxilla and 56 in the mandible, with this difference being statistically significant (P<0.05). Among the 293 impacted canines, 14 (4.8%) transmigrated canines were detected. From the 14 transmigrant canines, 13 were in the mandible and 1 was in the maxilla. This difference was found statistically significant (P<0.05). Eighteen dentigerous cysts (10 maxilla, 8 mandible) and 4 odontomas (3 maxilla, 1 mandible) were found in impacted canines. For a total of 293 impacted canines, 57 were extracted, 13 were referred to orthodontics and a follow-up decision was made for 223 teeth. CONCLUSIONS: Transmigration incidence is statistically significant, on a higher area of the lower jaw, compared to the upper jaw (P<0.05). In patients with impacted canines, taking CBCT together with a detailed clinical examination is effective in correct treatment planning and in minimizing complications that may occur during surgical extraction.

Calcifying odontogenic cyst resembling clinical signs of vertical root fracture of a maxillary canine.

BACKGROUND: Calcifying odontogenic cyst (COC) can be misdiagnosed as a lesion of endodontic origin when it is in close proximity to the periradicular tissue, and pulp sensibility tests are indispensable for differential diagnosis. However, when the adjacent teeth are necrotic or already endodontically treated, diagnosis becomes challenging. CASE DESCRIPTION: In this case report, a maxillary canine with an inadequate root canal treatment was considered as the source of an endodontic infection. Eight months after the retreatment, the patient sought treatment for a buccal intraoral swelling and a deep periodontal pocket and was referred for cone-beam computed tomography with a provisional diagnosis of a vertical root fracture. The tomography revealed an extensive lesion buccally to the roots of the canine and the adjacent vital lateral incisor. An unusual extended external resorption of the root of the vital lateral incisor was also evident. This finding shifted the diagnostic thinking toward a lesion of nonendodontic origin. The lesion was surgically enucleated, and the histopathologic examination confirmed the diagnosis of a COC. PRACTICAL IMPLICATIONS: Clinicians always must bear in mind the chance of a nonendodontic lesion masquerading as a lesion of endodontic origin. Cone-beam computed tomography should be considered in cases of doubt or in lesions refractory to endodontic treatment, as it can provide information on the clinicopathologic features of the lesion.

Equine Odontoclastic Tooth Resorption and Hypercementosis.

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a recently described painful and progressive condition of unknown etiology that occurs in middle-aged and geriatric equines. It predominantly affects the permanent incisor and canine teeth and, less commonly, the premolar and molar dentition. EOTRH was first reported in peer-reviewed literature in 2008, with subsequent publications of case reports, histological studies and retrospective case series. There have been few significant research developments related to this disease. The existing studies have primarily involved single case studies or small sample sizes, without control groups. This review aimed to report current information about EOTRH in terms of clinical, histopathological, diagnostic, radiological, and therapeutic aspects, by searching the available peer-reviewed scientific literature.

Role of reduced enamel epithelium in root resorption.

BACKGROUND: The precise mechanism of root resorption in human primary teeth is unclear. However, research has suggested that the enamel organ and dental follicle of the successive (permanent) teeth are important for this process. This review focuses on the mechanism of root resorption. HIGHLIGHT: Impaction of the maxillary permanent canines is occasionally seen. Computer tomography studies have shown that these canines cause root resorption in 12.5% of the neighboring central and lateral incisors. In such cases, enlargement of the radiolucent areas around the canine crowns is frequently seen. These radiolucent areas include dental follicles and reduced enamel epithelium, which are composed of degraded ameloblasts and cells of the papillary layer. Root resorbing factors, expressed from the reduced enamel epithelium, are likely to induce the odontoclastic root resorption. Physiological root resorption of the primary teeth is generally milder than this pathological root resorption, but involvement of the reduced enamel epithelium of the permanent tooth can be also proposed. CONCLUSION: This review highlights the role of the reduced enamel epithelium in root resorption under both pathological and physiological conditions.

Effects of Skeletally Supported Anterior en Masse Retraction with Varied Lever Arm Lengths and Locations in Lingual Orthodontic Treatment: A 3D Finite Element Study.

OBJECTIVE: This study is aimed at analyzing different points of force application during miniscrew supported en masse retraction of the anterior maxillary teeth to identify the best line of action of force in lingual orthodontic treatment. MATERIALS AND METHODS: Three-dimensional (3D) finite element models were created to stimulate en masse retraction with different heights and positions of the miniscrew and lever arm to change the force application points; a 150 g retraction force was applied from the miniscrew to the lever arms, and the initial tooth displacements were analyzed. RESULTS: Lingual crown tipping and occlusal crown extrusion were seen at all heights and positions of the miniscrew and lever arm, but when the miniscrew height was at 8 mm and the power arm was located between the lateral incisors and canines, these tipping patterns were less than those obtained with a 4.5 mm high miniscrew and a lever arm located distal to the canines. CONCLUSION: All miniscrew heights and lever arm positions showed initial lingual crown tipping and labial root tipping with occlusal crown extrusion. However, the 8 mm miniscrew height and the lever arm located between the lateral incisor and canine showed fewer amounts of these tipping patterns than a 4.5 mm miniscrew height and lever arm located distal to the canines. Therefore, this could be the preferred point of force application during en masse retraction in lingual treatment with additional torque control methods.

The Effect of Partial Corticotomy on the Rate of Maxillary Canine Retraction: Clinical and Radiographic Study.

The study aimed to evaluate, clinically and radiographically, the effect of partial corticotomy of the buccal plate distal to the canine on the rate of maxillary canine retraction. A clinical trial with the split-mouth design was conducted among twenty orthodontic patients, recommended for first premolar extraction with an age range from 13 to 21 years, selected from patients seeking orthodontic treatment in private dental clinics in Jeddah, Kingdom of Saudi Arabia. After extraction of the maxillary right and left first premolar, partial corticotomy was performed distal to the canine on the right side. The canine retraction was carried out with a power chain on both sides extended between the canine and the maxillary first molar. The data collected from the current study were tabulated and statistically analyzed using an independent sample t-test with p < 0.05 considered statistically significant. The rate of canine retraction was significantly higher on the corticotomy side than the control side (p < 0.05). Under the limitations of the present study, it can be concluded that the technique of partial corticotomy of the buccal plate distal to the canine is a straightforward surgical procedure enhancing the rate of canine retraction significantly.

Comparison of the collum angle of incisors and canines in skeletal malocclusions - A CBCT study.

INTRODUCTION: The collum angle that defines the crown root angulation of the single rooted teeth plays an important in treatment planning. OBJECTIVE: To compare the collum angle (crown root angulation) of maxillary and mandibular anterior teeth in different skeletal malocclusions using Cone Beam Computed Tomography (CBCT). MATERIALS AND METHODS: Sixty subjects were categorized into four groups (fifteen subjects in each group) Class I, Class II division 1, Class II division 2 malocclusion and Class III based on Angle classification, Wits and ANB. The collum angle of maxillary and mandibular anterior teeth was measured using CBCT. One way ANOVA, Post hoc comparison with Tukey HSD and Paired t-test were used to analyse the measured data. RESULTS: The collum angle of corresponding right and left side teeth were averaged. Thus, the mean and standard deviation of the collum angle (n-30) were generated for maxillary and mandibular central incisors, lateral incisors, and canines. A statistically significant increase was observed in the maxillary central incisors of Class II division 2 and mandibular lateral incisors of class III malocclusion. The collum angle was increased in mandibular canines of Class III malocclusion when compared with class I and Class II division 2 malocclusion. The collum angle was negative in mandibular central incisors of Class II division 2. No statistically significant difference was observed in the mean collum angle between the right and left side anterior teeth in all the four groups. CONCLUSION: A variation in Collum angle was observed between the maxillary and mandibular anterior teeth and malocclusions. The effect of these variations in collum angle in torque expression and biomechanics should be kept in mind by the orthodontist before treatment planning especially in Class II division 2 malocclusion.

Exophytic gingival growth of the maxillary canine region in a young individual: Extremely rare case report of peripheral dentinogenic ghost cell tumor.

The present case report is a case of peripheral dentinogenic ghost cell tumor (PDGCT), an extremely rare solid benign neoplastic variant of calcifying cystic odontogenic tumor of the gingiva mimicking clinically as pyogenic granuloma, fibroma, peripheral ossifying fibroma, and peripheral giant-cell granuloma. A 24-year-old male reported with painless, firm, solitary, sessile, smooth-surfaced, nonulcerative, nonpulsatile, well-defined swelling measuring ≈12 mm × 9 mm in the interdental gingiva of the teeth #13 and #14 extending to the mucogingival junction. Intraoral periapical radiographic showed a normal trabecular pattern with mild radiolucency without bony expansion, periapical lesion, and resorption of the adjacent teeth. The diagnosis was established by histopathologic examination. Very few cases of this entity have been documented in the literature. The present case report aims to document this rare entity and emphasizes on the fact that histopathological examination of every localized gingival growth should be included in the treatment planning to differentiate with other commonly found lesions.

Root changes in buccal versus palatal maxillary impacted canines of adults: A longitudinal and retrospective 3-dimensional study before and after orthodontic traction.

OBJECTIVE: Maxillary impacted canines (MIC) could suffer root changes after canine traction. The aim of this study was to evaluate the 3-dimensional root changes in buccal versus palatal MIC after orthodontic traction. MATERIALS AND METHODS: This longitudinal and retrospective study included pre-treatment and after traction cone beam computed tomography scans (CBCTs) of 30 subjects with unilateral/bilateral MIC. A total of 43 MIC were divided into 2 groups: buccal (n=17) or palatal (n=26). Root changes in length and area after orthodontic traction were measured at sagittal, coronal and axial sections. Intergroup comparison was carried out by t or U Mann-Whitney tests, depending on normality. Multiple linear regression analysis was used to evaluate the influence of all predictor variables on root changes (P<0.05). RESULTS: Significant difference between groups was found for root area changes in the upper limit of the cervical third at axial section that showed greater appositional values for the palatal impacted canine group (-1.18mm2) and resorptive values for the buccal impacted canine group (0.62mm2) (P=0.024). Position of impaction palatal influenced the increase of root area in the coronal section and in the upper limit of the cervical third at axial section. Age directly influenced the decrease of total length and root area in sagittal and coronal sections, respectively. CONCLUSION: Orthodontic traction of MIC produced an important appositional root change in the palatal impaction group in the axial root area of the upper limit of the cervical third. Impaction position and age influenced the increase and decrease of root area and length of some specific radicular regions.

Inter-premolar width changes related to the orthodontic traction of maxillary impacted canines in adolescents and young adults: A retrospective CBCT study.

OBJECTIVE: Maxillary canine impaction is directly associated with a narrow maxillary arch, mainly in the inter-premolar widths. This study compared the transverse changes at the level of maxillary premolars after traction of maxillary impacted canines (MICs) in adolescents and young adults through three main goals: to compare unilateral versus bilateral cases, to compare buccally versus palatally MIC cases, and to compare the affected versus non-affected side exclusively in the unilateral group. METHODS: This before and after CBCT study involved 45 MIC orthodontically tractioned until the occlusal plane with a standardized protocol. The sample was classified regarding the impaction type (unilateral versus bilateral), impaction location (palatal versus buccal) and the affected versus unaffected sides in the unilateral cases. MIC characteristics as impaction sector, height, and complexity of the traction, as well as α and ß angles, canine root length and area were measured. Moreover, cephalometric characteristics were also evaluated. Mann-Whitney U or Wilcoxon signed-rank tests and multiple regressions were applied (α=0.05). RESULTS: Maxillary inter-premolar widths (first or second) expanded approximately 3mm after traction of unilateral or bilateral MIC (P>0.05). Changes in hemi-arch widths between palatal (1.67mm) versus buccal (1.90mm) MIC were similar (P>0.05). In unilateral impaction, the transversal changes on the affected side were 2mm versus almost 1mm observed in the unaffected side (P<0.05). Finally, the multiple linear regressions were identified to the ANB angle, the impaction sectors and the distance from middle raphe to the cusp tip of MIC as influential variables. CONCLUSION: The maxillary inter-premolar widths increase after traction of MIC without differences between type or location of impaction. In addition, the transverse change in the affected side in unilateral MIC is greater than the unaffected side resolving the earlier transverse asymmetry.

Impactación Canina Maxilar y Reabsorción Radicular de Dientes Adyacentes: Un Análisis a Través de Tomografía Computarizada Cone-Beam / Canine Maxillary Impaction and Root Resorption of Adjacent Teeth: An Analysis through Cone-Beam Computed Tomography Analysis

RESUMEN: Uno de los problemas con mayores consecuencias tanto estéticas como funcionales en ortodoncia es la impactación de caninos maxilares (ICM) siendo principal motivo de reabsorciones radiculares de dientes adyacentes. Actualmente se carece de estudios que describan la reabsorción radicular por ICM a través de tomografía computarizada conebeam (TCCB) en la población chilena. El objetivo del estudio fue describir a pacientes entre 8 a 18 años, que presentan ICM (o riesgo de ella), tanto en las características de la impactación canina como en la reabsorción radicular presentada en incisivos laterales (IL) y en otros dientes adyacentes. En este estudio retrospectivo, 135 datos de TCCB fueron seleccionados por conveniencia, de los cuales 181 caninos presentaron ICM. Fueron analizadas las variables edad, sexo, tipo de ICM (unilateral o bilateral), localización bucolingual (vestibular o palatino), lado de impactación (derecho o izquierdo), reabsorción radicular en el incisivo lateral y registro de el o los dientes anexos afectados por reabsorción radicular (incisivo central y/o premolares). Además en el caso de reabsorción de IL fue analizada la reabsorción tridimensionalmente a través de la ThreeDimensional Leeds Orthodontic Root Resorption Target Scale (3D-LORTS). La ICM en la muestra seleccionada tuvo una edad promedio de 12 años, una relación por sexo mujeres:hombres de 1,5:1, frecuentemente de tipo unilateral, en el lado derecho y una localización bucolingual palatina (64,1 %) por sobre la vestibular (35,9 %). La reabsorción radicular alcanzó un 35,9 %, de la cual un 27,6 % involucró a IL y un 8,3 % en dientes anexos adyacentes. En cuanto a la distribución tridimensional de la reabsorción radicular, la más frecuente involucró el tercio apical (60 %), con compromiso pulpar o severo (40 %), involucrando solo una cara, la palatina (54 %). Ninguna de las variables anteriores consideradas, demostró diferencias estadísticas con la reabsorción radicular de incisivos laterales.

ABSTRACT: One of the problems with greatest aesthetic and functional consequences in orthodontics is the Impaction of Maxillary Canines (ICM) being the main reason for root resorption of the adjacent teeth. Currently there are no studies describing root resorption by ICM through cone beam computed tomography (CBCT) in the Chilean population. The main objective of the study was to describe patients between 8 and 18 years old, who presented with ICM (or risk thereof), with the characteristics of canine impaction as well as root resorption presented in lateral incisors (IL) and in other adjacent teeth. In this retrospective study, 135 CBCT subjects were selected for convenience, of which 181 canines presented ICM. The variables were analyzed: age, sex, type of ICM (unilateral or bilateral), buccolingual location (vestibular or palatal), side of impaction (right or left), root resorption in the lateral incisor and registration of adjacent teeth affected by resorption radicular (central incisor and/or premolars). In addition, when reabsorption of IL was observed, three-dimensional analysis was made using the Three-Dimensional Leeds Orthodontic Root Resorption Target Scale (3D-LORTS). The ICM in the selected sample had an average age of 12 years, a ratio by sex of women:men of 1.5:1, frequently of unilateral type, on the right side and with palatine buccolingual location (64.1 %) above the vestibular (35.9 %). Root resorption reached 35.9 %, of which 27.6 % presented in the IL and 8.3 % in adjacent teeth. Regarding the three-dimensional distribution of root resorption, the most frequent involved the apical third (60 %), with pulpal or severe damage (40 %), in only one location, the palatine (54 %). None of the above variables considered showed statistical differences with the root resorption of lateral incisors.

Sella turcica and craniofacial morphology in patients with palatally displaced canines: a retrospective study.

BACKGROUND: The aim of the study was to evaluate the sella and craniofacial morphological features in growing patients with palatally displaced canines compared to controls. MATERIALS AND METHODS: Twenty-two subjects with palatally displaced canines were retrospectively selected and compared to 22 controls matched for age and gender. Lateral cephalograms were collected and sagittal and vertical cephalometric variables were measured, together with sella interclinoid distance, sella depth, and sella diameter. The independent samples T-test or Mann-Whitney U-test were used to compare all the variables between the two groups. A Pearson correlation was computed for the craniofacial and sella variables that differed significantly (p < 0.05) between the groups. RESULTS: Patients with palatally displaced canines showed a smaller interclinoid distance and a greater SNA angle than control subjects. The interclinoid distance and the SNA angle were negatively correlated (-0.52, p = 0.017) in the experimental group. CONCLUSIONS: Growing patients with palatally displaced canines had smaller sella interclinoid distances and a greater SNA angle than control subjects.

In silico study of cuspid' periodontal ligament damage under parafunctional and traumatic conditions of whole-mouth occlusions. A patient-specific evaluation.

BACKGROUND AND OBJECTIVE: Although traumatic loading has been associated with periodontal ligament (PDL) damage and therefore with several oral disorders, the damage phenomena and the traumatic loads involved are still unclear. The complex composition and extremely thin size of the PDL make experimentation difficult, requiring computational studies that consider the macroscopic loading conditions, the microscopic composition and fine detailed geometry of the tissue. In this study, a new methodology to analyse the damage phenomena in the collagen network and the extracellular matrix of the PDL caused by parafunctional and traumatic occlusal forces was proposed. METHODS: The entire human mandible and a portion thereof containing a full cuspid tooth were separately modelled using finite element analysis based on computed tomography and micro-computed tomography images, respectively. The first model was experimentally validated by occlusion analysis and subjected to the muscle loads produced during hard and soft chewing, traumatic cuspid occlusion, grinding, clenching, and simultaneous grinding and clenching. The occlusal forces computed by the first model were subsequently applied to the single tooth model to evaluate damage to the collagen network and the extracellular matrix of the PDL. RESULTS: Early occlusal contact on the left cuspid tooth guided the mandible to the more occluded side (16.5% greater in the right side) and absorbed most of the lateral load. The intrusive occlusal loads on the posterior teeth were 0.77-13.3% greater than those on the cuspid. According to our findings, damage to the collagen network and the extracellular matrix of the PDL could occur in traumatic and grinding conditions, mainly due to fibre overstretching (>60%) and interstitial fluid overpressure (>4.7 kPa), respectively. CONCLUSIONS: Our findings provide important biomechanical insights into the determination of damage mechanisms which are caused by mechanical loading and the key role of the porous-fibrous behaviour of the PDL in parafunctional and traumatic loading scenarios. Besides, the 3D loading conditions computed from occlusal contacts will help future studies in the design of new orthodontics appliances and encourage the application of computing methods in medical practice.

Bilateral canine space infection secondary to odontogenic origin: a rare case report

Odontogenic infections (OI) are a major reason for consultation in dental practice. They affect people of all ages, and most of them respond well to current medical and surgical treatments. The aim of this paper is to emphasize different and rare etiological factors that can play a role in odontogenic abscesses, which can lead to complications. A 54-year-old man complaints of pain and swelling on the upper front-side of his face. Physical examination of the face showed enlargement and swelling in the upper front region. Panoramic radiograph images showed a ra-diolucent appearance of the canine region. Based on the results of the clinical and radiographic examinations, the patient was diagnosed with a bilateral canine space infection. The treatment performed was FNAC (Fine neddle aspiration cytology) from canine region followed by intraoral drainage incision at the most prominent part of swelling (Modified Hiltons method), 5 ml of pus was removed, postoperative dressing was applied and regular follow-up was done with continued antibiotic therapy. Bilateral canine space abscess is a rare odontogenic infection that can cause life-threatening complications. The success of treatment requires early recognition, determination of etiological factors, and appropriate medical and surgical management. To per-form treatment of odontogenic infections, the Oral & Maxillofacial Surgeon should understand the terminology regarding infectious diseases and pathophysiology. The success of treatment requires early recognition, determination of etiological factors, and appropriate medical and surgical management.

History, clinical findings and outcome of horses with radiographical signs of equine odontoclastic tooth resorption and hypercementosis.

The progression of equine odontoclastic tooth resorption and hypercementosis (EOTRH) has not been completely evaluated, and currently, the only effective treatment is extraction of severely affected teeth. We aim to describe how the disease relates to the history and clinical findings and to report on the outcome in individual horses. This case series comprises data collected from 20 horses (age 14-29 years old) with radiographic findings of EOTRH in their incisor and/or canine teeth. Most horses affected with EOTRH in this study were admitted for dental problems, but some for other complaints such as colic. Of the 288 teeth evaluated radiographically, 224 teeth were abnormal. Radiographic findings were most frequently located in the apical aspect and reserve crown of the teeth, and lesions were also commonly found in clinically normal teeth. Histopathology of extracted teeth showed inflammation in the periodontal ligament and revealed that resorption often extended to the dentine. Some owners were unwilling to allow extraction of their horses' severely affected teeth, even though this treatment has been shown to increase the wellbeing of the horse. As EORTH is a life-long condition, the progression of the disease has to be continuously monitored and the treatments adjusted accordingly.

Cheek tooth erosion in male babirusa (genus Babyrousa).

The wear on the occlusal surfaces of male babirusa cheek teeth was evaluated in 53 skulls of Babyrousa babyrussa from Buru and the Sula Islands and 87 skulls of B. celebensis from Sulawesi, Indonesia. Based on the comparative lengths of their continually growing maxillary canine teeth, the skulls were divided into five 'age categories' (A-E). Numerical and symbolic codes representing tooth wear were applied to each pillar (cusp region) of the mandibular and maxillary permanent third and fourth premolar teeth, and the first, second and third permanent molar teeth. There was no significant difference between the tooth wear patters of skulls in groups A and B, or in groups C and D, and so these were amalgamated. There was close correspondence in wear patterns between each side of the mouth in both species and in each age group. The wear patterns of the mandibular and maxillary teeth, although not identical, were very similar, as were the wear patterns of both species. In group A+B for both species tooth wear was relatively slight, with the M1 teeth experiencing most relative wear. There was almost no wear of the M3 teeth. In group C+D substantial wear of upper and lower M1 was evident. In group E more widespread wear of the cheek teeth was seen, with increased severity of M1 tooth wear, yet there was comparatively much less M2 and M3 tooth wear. The pattern of cheek tooth wear of the Babyrousa spp. was different from that shown by Susscrofa. Differences in diet selection and processing were highlighted as potential contributing factors. The pattern of cheek tooth wear in male babirusa was not adequate for use to monitor their age.

Finite element analysis of the effect of power arm locations on tooth movement in extraction space closure with miniscrew anchorage in customized lingual orthodontic treatment.

INTRODUCTION: More patients are choosing customized orthodontic appliances because of their excellent esthetics. It is essential that clinicians understand the biomechanics of the tooth movement tendency in customized lingual orthodontics. This study aimed to evaluate the tooth movement tendency during space closure in maxillary anterior teeth with the use of miniscrew anchorage in customized lingual orthodontics with various power arm locations. METHODS: Three-dimensional finite element models of the maxilla were created with miniscrews and power arms; the positions were varied to change the force directions. A retraction force (1.5 N) was applied from the top of the miniscrews to the selected points on the power arm, and the initial displacements of the reference nodes of the maxillary teeth were analyzed. RESULTS: After applying force in different directions, power arms located at the distal side of the canines led to larger initial lingual crown tipping and occlusal crown extrusion of the maxillary incisors compared with power arms located at the midpoint between the lateral incisors and canines, and caused a decreasing trend of the intercanine width. CONCLUSIONS: In customized lingual orthodontic treatment, power arms located at the distal side of the canines are unfavorable for anterior teeth torque control and intercanine width control. Power arms located at the midpoint between the lateral incisors and canines can get better torque control, but still cannot achieve excepted torque without extra torque control methods, no matter whether its force application point is higher than, lower than, or equal to the level of the top of the miniscrews.

Association between maxillary transverse discrepancy and occurrence of potentially impacted maxillary canines in mixed dentition patients.

OBJECTIVE: The aim of this study was to determine the association between transverse maxillary discrepancy and occurrence of potentially impacted maxillary canines in mixed dentition patients. MATERIAL AND METHODS: This cross-sectional analytical study was conducted on 85 Pakistani subjects (32 males and 53 females) aged between 8 to 13 years, having good quality orthopantomographs and dental casts. Maxillary transverse discrepancy was assessed by subtracting the mandibular intermolar width from the maxillary intermolar width on dental cast. Maxillary lateral incisors and canines were traced from orthopantomographs, and canines were placed into sector classification. Chi-square test was used to determine the difference in the occurrence of potentially impacted maxillary canines between patients with maxillary transverse discrepancy and patients without maxillary transverse discrepancy. RESULTS: There was no significant difference seen in the occurrence of impacted maxillary canines in patients with and without maxillary transverse discrepancy in mixed dentition patients. CONCLUSION: Patients with maxillary transverse discrepancy may not be at a higher risk of palatal canine impaction. Radiological presence of canine in sector II, III and IV, pose a higher risk of canine impaction.

The effect of NaOCl and heat treatment on static and dynamic mechanical properties and chemical changes of dentine.

OBJECTIVES: To determine the effect of heat on flexural strength (FS), maximum strain (MS), storage modulus (SM), tan delta (TD) and chemical changes through micro-Raman spectroscopy of dentine exposed to 2.5% NaOCl or saline. METHOD: ology: Dentine bars were randomly allocated to 8 test groups. Half (groups 2,4,6,8) were treated with NaOCl for 20 min; the rest (groups 1,3,5,7) remained in saline. FS/MS were measured in groups 1-4 (n = 15) (3/4 were also heated to 200 °C & re-hydrated in saline). Micro-Raman spectroscopy was performed on bars from groups 1-4. SM/TD were measured in 5-8: in 5/6 (n = 10), repeated after heating (200 °C), then following re-hydration; in 7/8 (n = 3) after heating to 25-185 °C. RESULTS: Increase in MS on heat and FS/MS on heat + NaOCl was not significant (P > 0.05). SM increased (P = 0.06) after heat treatment but reduced to initial state after rehydration (P = 0.03). TD did not change (P = 0.4) after heat (200 °C) treatment but rehydration increased it compared with pre-treatment state (P = 0.001). For dentine bars pre-treated with NaOCl, SM did not change (P = 0.6) after heat (200 °C) treatment or rehydration but TD significantly increased (P = 0.02) upon re-hydration compared with pre- (P=0.007), or post- (P = 0.03) heat-treatment states. SM and TD varied between 25-185 °C with no consistent trend amongst the NaOCl pre-treated bars. Micro-Raman only detected chemical changes following NaOCl treatment in the mineral phase. CONCLUSIONS: Exposure of dentine bars to heat and NaOCl produced only moderate changes to quasi-static but marked changes to viscoelastic properties, which may be explained by chemical alterations.